JP7324044B2 - Ignition system and combustor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ignition system and a combustor, and more particularly to an ignition system and a combustor using flame-retardant ammonia or the like as fuel.

In recent years, along with the demand for reduction of carbon dioxide emissions, expectations are rising for ammonia, which does not emit carbon dioxide when burned, as a fuel to replace carbon-based fuels. On the other hand, ammonia, which is a flame-retardant fuel, has characteristics that it is difficult to ignite (ignite) and has a slow burning speed as compared with carbon-based fuels. Specifically, while the energy required to ignite carbonaceous fuel is about 80 mJ to 120 mJ, the energy required to ignite ammonia is about 400 mJ to 600 mJ. The laminar burning velocity of ammonia is approximately seven times slower than the laminar burning velocity of carbonaceous fuels (for example, common hydrocarbon fuels such as methane and propane).

In an ignition system in a combustor using this flame-retardant ammonia as fuel, unburned ammonia and nitrogen oxides may be produced due to incomplete combustion of the fuel. Therefore, various techniques for efficiently burning ammonia have been proposed. For example, there is a technique for efficiently burning flame-retardant ammonia by supplying flammable hydrogen gas (hydrogen molecules) before burning ammonia, igniting this hydrogen gas first, and then supplying ammonia. .

On the other hand, there is a technique of generating hydrogen gas using ammonia as a raw material gas (see, for example, Patent Document 1). In Patent Document 1, a dielectric barrier discharge is generated between the electrodes by applying a voltage to the electrodes from a high-voltage power supply, and after the ammonia is brought into an atmospheric pressure non-equilibrium plasma state by the discharge, Techniques for extracting hydrogen atoms and recombining them to produce hydrogen gas have been disclosed.

Japanese Patent No. 6241804

However, in the technology for efficiently burning ammonia described above, if the technology of Patent Document 1 is adopted for generating the required hydrogen gas, a separate control device for generating the dielectric barrier discharge is required, and an emergency occurs. However, there is a problem that the cost is high.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an ignition system or the like that efficiently burns flame-retardant ammonia without adding a new control device.

An ignition system according to the present invention includes an ignition coil having a primary coil through which a primary current flows, a secondary coil that generates a secondary current by increasing or decreasing the primary current, and a discharger electrically connected to the secondary coil. A spark plug having an electrode at one end and a dielectric barrier discharge reactor for generating a dielectric barrier discharge are provided, and the discharge electrode of the spark plug and the dielectric barrier discharge reactor are electrically connected.

In the ignition system of the present invention, the same pulse signal can be used to perform ignition discharge to the spark plug and dielectric barrier discharge for plasmatizing highly flame-retardant ammonia gas. Therefore, in the technology for efficiently burning ammonia described above, there is no need for a separate control device for generating the dielectric barrier discharge to generate the required hydrogen gas, thereby suppressing an increase in manufacturing costs. becomes possible.

In one embodiment of the ignition system, a Zener diode or resistor is connected between the secondary coil and the discharge electrode of the spark plug.

The ignition system of the present invention makes it possible to adjust the energy supplied from the secondary coil to the spark plug.

In one embodiment of the ignition system, a Zener diode or resistor is connected between the secondary coil and the dielectric barrier discharge reactor.

The ignition system of the present invention makes it possible to adjust the energy supplied from the secondary coil to the dielectric barrier discharge reactor.

In one embodiment, the ignition system further includes a battery connected to the primary coil, and an ignition coil drive circuit for controlling an increase or decrease in the primary current of the primary coil, wherein the ignition coil drive circuit a switching element connected to a primary coil; and a drive section for controlling energization or cutoff of the switching element, wherein the drive section controls the voltage of the battery and the voltage between the primary coil and the switching element. to control energization or cutoff of the switching element based on at least one voltage of

In the ignition system of the present invention, the voltage across the secondary coil is a value obtained by multiplying the voltage across the primary coil by the turns ratio, so the value of the voltage across the secondary coil can be easily grasped. It becomes possible.

In one embodiment, the ignition system further includes a reformer that reforms ammonia gas by the dielectric barrier discharge to generate hydrogen gas that is more combustible than ammonia gas, and the driving unit includes the reforming controlling the dielectric barrier discharge in the vessel;

In the ignition system of the present invention, the drive unit that controls the ignition operation of the spark plug can control dielectric barrier discharge that reforms ammonia gas to generate hydrogen gas that is more combustible than ammonia gas. Become. Therefore, in the technology for efficiently burning ammonia gas described above, there is no need for a separate control device for generating dielectric barrier discharge to generate the required hydrogen gas, thereby suppressing an increase in manufacturing costs. becomes possible.

In another aspect, the combustor of the present invention comprises:
a combustor body in which the supplied fuel is burned;
a swirler provided in the combustor body for feeding the first fuel into the combustor body as a swirling airflow;
a reformer that reforms the first fuel by dielectric barrier discharge to produce a second fuel having higher combustibility than the first fuel;
a pilot burner that ejects a second fuel having higher combustibility than the first fuel into the combustor body;
a spark plug that ignites the pilot burner;
and a control means for controlling the ignition operation of the spark plug,
The control means controls the dielectric barrier discharge in the reformer.

In the combustor of the present invention, the control means for controlling the ignition operation of the spark plug controls dielectric barrier discharge for reforming the first fuel to produce the second fuel having higher combustibility than the first fuel. becomes possible. Therefore, in the technology for efficiently burning ammonia gas described above, there is no need for a separate control device for generating dielectric barrier discharge to generate the required hydrogen gas, thereby suppressing an increase in manufacturing costs. becomes possible.

In one embodiment of the combustor, the first fuel is ammonia gas and the second fuel is hydrogen gas.

In the combustor of this embodiment, the first fuel is ammonia gas and the second fuel is hydrogen gas, so that the pilot flame burns the premixed gas to form a premixed flame. Be efficient.

According to the ignition system of the present invention, the control device for controlling the ignition discharge to the spark plug and the control device for controlling the dielectric barrier discharge for plasmatizing the highly flame-retardant ammonia gas are shared. becomes possible. Therefore, in the technology for efficiently burning ammonia described above, there is no need for a separate control device for generating the dielectric barrier discharge to generate the required hydrogen gas, thereby suppressing an increase in manufacturing costs. becomes possible.

1 is a partially cutaway side view of a combustor 2 according to an embodiment of the present invention and a block diagram showing its peripheral components. FIG. FIG. 2 is a block diagram showing components of an ignition system 10 including the control device 1 of FIG. 1; FIG. 3 is a timing chart of each signal showing the operation of the ignition system 10 of FIG. 2;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

embodiment.
FIG. 1 is a partially cutaway side view of a combustor 2 according to an embodiment of the present invention and a block diagram showing its peripheral components. The combustor 2 in FIG. 1 is made of cylindrical heat-resistant glass or stainless steel, and includes a combustor body 4 in which the supplied fuel is burned, and a circular combustor body 4 into which the fuel is fed. an inlet 22, a swirler (swirling vane) 23 located in the inlet 22 and provided in the combustor body 4, and a fuel tank 12a for storing highly flame-retardant ammonia gas (first fuel). , a reformer, which is a hydrogen generating device that reforms ammonia gas by dielectric barrier discharge to generate hydrogen gas (second fuel) that is more combustible than the ammonia gas, and supplies the hydrogen gas to the combustor main body 4; 13, an air compressor 12b that supplies air as an oxidant, valves 21 that adjust the supply amounts of ammonia gas, hydrogen gas, and air, respectively, and a pilot burner 14 supported on the bottom 18 of the combustor body 4; In the vicinity of the pilot burner 14, a spark plug 7 for igniting the pilot burner 14, and a control device 1 as a control means for controlling both the ignition operation of the spark plug 7 and the dielectric barrier discharge in the reformer 13 are provided. configured with.

The spark plug 7 of FIG. 1 has a discharge electrode 7a with a hook-shaped tip and a ground electrode 7b with a hook-shaped tip. are formed so as to protrude into the interior of the . A high voltage was applied to the discharge electrode 7a from the control device 1, whereby a spark was generated between the tip of the discharge electrode 7a and the tip of the ground electrode 7b, and was ejected from the pilot burner 14. It is ignited by hydrogen gas.

The combustor body 4 shown in FIG. and a bottom portion 18 covering the side opening. A circular inlet 22 through which the flame-retardant ammonia gas is fed into the combustor main body 4 is provided in the central portion (central portion) of the bottom portion 18 in FIG. 1 . In addition, an output port 24 through which flames are ejected is provided in the central portion of the lid portion 20 of FIG.

The swirler 23 is supported on the bottom portion 18 of the combustor body 4 near the center when the combustor body 4 is horizontally cut. Through this swirler 23, the ammonia gas is sent into the combustor main body 4 as a swirling airflow S1. Here, the ammonia gas is supplied to the combustor main body 4 as a whirling airflow S1 by adjusting the valve 21 connected to the fuel tank 12a and the valve 21 connected to the air compressor 12b. It is possible to send. The swirling airflow S1 that has flowed in from the inlet 22 spreads along the inner wall (inner peripheral surface) of the combustor main body 4 while advancing upward. The ammonia gas in the central portion of the combustor main body 4 is pulled by this flow, and in the central portion of the combustor main body 4, the ammonia gas flows upward while swirling.

In addition, a plurality of pilot burners 14 are arranged outside the swirler 23 . More specifically, a plurality of pilot burners 14 are arranged in the vicinity of the inner wall of the combustor main body 4 at equal pitches in the circumferential direction so as to be concentric with the swirler 23 and surround the peripheral edge of the inlet 22 (the peripheral edge of the swirler 23). It is installed and ejects hydrogen gas, which is more combustible than ammonia gas. Here, by adjusting the valve 21 connected to the reformer 13 and the valve 21 connected to the air compressor 12b, it is possible to send hydrogen gas of a predetermined concentration to each pilot burner 14. becomes.

The reformer 13 in FIG. 1 includes a dielectric that defines an ammonia gas flow path, a high voltage electrode that is arranged in contact with the dielectric, a high voltage electrode that faces the dielectric across the dielectric, and is grounded. A bipolar pulse waveform is applied to a hydrogen separation membrane that functions as an electrode, a hydrogen flow path that leads to hydrogen separated by the hydrogen separation membrane, and a high voltage electrode, and a gap between the hydrogen separation membrane and the high voltage electrode is applied. and a high voltage power supply for generating a dielectric barrier discharge at. Here, it becomes possible to generate hydrogen gas from ammonia gas at a high yield by the discharge action between the hydrogen separation membrane and the high-voltage electrode. That is, the reformer 13 of FIG. 1 is a plasma type hydrogen generator.

FIG. 2 is a block diagram showing components of an ignition system 10 including the controller 1 of FIG. Ignition system 10 of FIG. and a control device 1 which is control means for controlling the dielectric barrier discharge. Here, the discharge electrode 7a of the spark plug 7 and the dielectric barrier discharge reactor 8 are electrically connected.

The control device 1 shown in FIG. 2 includes an ignition coil drive circuit 30, an ignition coil 5, and a battery 6, which is a power supply unit with a negative negative terminal grounded. The ignition coil 5 includes a primary coil L1, a secondary coil L2, and an iron core. One end of the primary coil L1 is connected to one end of the secondary coil L2 and the + side terminal of the positive electrode of the battery 6, and the other end of the primary coil L1 is connected to an insulated gate described later via a primary current input terminal. It is connected to the collector terminal of a bipolar transistor (hereinafter simply referred to as “IGBT”) 31 . The other end of secondary coil L2 is electrically connected to spark plug 7 and dielectric barrier discharge reactor 8 .

The ignition coil drive circuit 30 includes a current detection section 40 that detects a voltage corresponding to the primary current I1 flowing through the primary coil L1, an IGBT 31 that is a switching element, and a drive section 32 that controls the switching operation of the IGBT 31. consists of Further, the current detection unit 40 includes a power supply 42 having a reference voltage Vref, a comparator 41, and a resistor 43 for detecting current flowing through the IGBT 31. FIG. Here, one end of the resistor 43 is connected to the emitter terminal E of the IGBT 31, and the other end of the resistor 43 is grounded.

The comparator 41 inputs the value of the voltage difference across the resistor 43 corresponding to the current I1 flowing through the IGBT 31 (the detected voltage corresponding to the primary current I1 flowing through the primary coil L1) to its non-inverting input terminal, and the value of the reference voltage Vref. to the inverting input terminal. Here, the comparator 41 compares the voltage difference between both ends of the resistor 43 and the value of the reference voltage Vref to generate the comparison result signal CO and output it to the driving section 32 . That is, the comparator 41 outputs a high level signal (H) as the comparison result signal CO when the voltage difference across the resistor 43 is greater than the reference voltage Vref, and the voltage difference across the resistor 43 is equal to or less than the reference voltage Vref. A low-level signal (L) is output as the comparison result signal CO at this time.

The drive unit 32 includes a CPU that performs control processing and arithmetic processing related to combustion control, various memories that store and hold data and programs required for combustion control, and the like. A pulse signal having a predetermined pulse width is generated as an ignition signal S, and based on the ignition signal S, energization or cutoff of the IGBT 31 is controlled. Further, based on the comparison result signal CO, the driving section 32 controls the voltage of the control terminal of the IGBT 31 so that the primary current I1 does not exceed a predetermined threshold value. That is, the current detection section 40 functions as an overcurrent protection circuit. Here, the various memories include nonvolatile recording media such as hard disks (HDD), flash memories, solid state drives (SSD), and the like.

The effects of the combustor 2 configured as described above will be described below.

In the method of burning fuel by the combustor 2 of FIG. 1, at the start of combustion, highly combustible hydrogen gas is sent to each pilot burner 14, and the hydrogen gas is first ignited. After igniting this hydrogen gas, highly flame-retardant ammonia gas is supplied.

Here, first, the hydrogen gas ejected from each pilot burner 14 is ignited by the spark plug 7 to form a pilot flame. Next, highly flame-retardant ammonia gas is sent into the combustor main body 4 via the swirler 23 as a swirling airflow S1. Here, the pilot flame of each pilot burner 14 spreads to the ammonia gas to form a premixed flame, and the flame is ejected from the output port 24 .

With this configuration, first, the highly combustible hydrogen gas is burned to form a stable flame in the circumferential direction, and then the efficiency of the flame transfer to the highly flame-retardant ammonia gas is improved. Combustion can be made more stable. Therefore, it is possible to stabilize the combustion of the ammonia gas more stably, so that the flame of the highly flame-retardant ammonia gas can be formed and the ammonia gas can be burned more stably. Here, the effect of "forming a flame of ammonia to stably burn ammonia" includes the effect of reducing combustion fluctuation, which is a state in which the combustion state of the fuel changes, and furthermore, the combustion is intermittent. It also includes the effect of reducing combustion oscillation, which is a phenomenon that causes the entire apparatus to vibrate due to the pulsation of the combustion gas pressure that occurs spontaneously.

As described above, in the combustor 2 of FIG. 1, before burning the highly flame-retardant ammonia gas, the highly combustible hydrogen gas is burned, and then the ammonia gas is ignited to stably burn the ammonia gas. I am letting In the present invention, dielectric barrier discharge is used to separate and generate hydrogen gas from ammonia gas, and this dielectric barrier discharge and the spark discharge of the ignition plug 7 are controlled by a common controller 1. . The operation of the ignition system 10 of FIG. 2 will now be described.

FIG. 3 is a timing chart of each signal showing the operation of the ignition system 10 of FIG. Here, FIG. 3 is a timing chart explaining the operation of the ignition system 10 when the ignition signal S, which is a pulse signal, is input to the IGBT 31. As shown in FIG.

FIG. 3(a) is a time-axis waveform diagram showing changes in the amplitude level of the ignition signal S with respect to time t, and FIG. 3(b) is a time-axis waveform diagram and elapsed time axis of the ignition signal S in FIG. , and is a time axis waveform diagram showing changes in the amplitude level of the secondary voltage V induced in the secondary coil L2 with respect to time t.

As shown in FIGS. 3(a) and 3(b), in the first one pulse, the ignition signal S input to the IGBT 31 that controls the energization and interruption of the primary current I1 flowing through the primary coil L1 changes from time t0 to time t1. It is a high level signal until Here, at time t0, the IGBT 31 is turned on to start supplying the primary current I1 to the primary coil L1, and the primary current I1 gradually increases due to the L component of the primary coil L1. At the same time when the primary current I1 starts to rise, the secondary voltage V steeply rises to the on-time voltage V3, and then gradually attenuates over the on period (time period T1) of the IGBT 31 . Due to the internal resistance of the battery 6 and the wiring resistance between the battery 6 and the primary coil L1, the voltage across the primary coil L1 gradually drops in accordance with the amount of the primary current I1 flowing through the primary coil L1. due to that. That is, since the voltage across the secondary coil L2 is a value obtained by multiplying the voltage across the primary coil L1 by the turns ratio of each coil, the voltage across the secondary coil L2 increases as the voltage across the primary coil L1 decreases. The secondary voltage V, which is the voltage across , gradually drops to voltage V4. As a result, a positive pulse voltage is applied to the dielectric barrier discharge reactor 8 .

Next, at time t1, the ignition signal S becomes low level, the IGBT 31 is cut off, and the primary current I1 becomes zero. As a result, when the primary current I1 fluctuates abruptly, the secondary coil L2 is accordingly excited to generate a high voltage of several hundreds of volts. In response to this high voltage, a spark discharge is generated in the spark plug 7 and a negative pulse voltage is applied to the dielectric barrier discharge reactor 8 to generate dielectric barrier discharge. Specifically, the polarity of the secondary voltage V generated in the secondary coil L2 at the timing when the IGBT 31 is cut off is opposite to the voltage drop when the IGBT 31 is on, and the secondary voltage V of the secondary coil L2 has a negative polarity. It sharply rises to the voltage (capacitor discharge voltage V1). Then, immediately after the secondary voltage V sharply rises, the secondary voltage V becomes the voltage V2 during the OFF period of the IGBT 31 (time period T2). The voltage V2 is called an induced discharge voltage, and is determined by the physical distance between the spark plug 7 and the dielectric barrier discharge reactor 8 and the like.

The on-time voltage V3 and the capacity discharge voltage V1 described above can be calculated by the following equations. Here, Vb is the power supply voltage of the battery 6, n1 is the number of turns of the primary coil L1, n2 is the number of turns of the secondary coil L2, Vcl is the clamp voltage of the IGBT 31, and V1 is the capacity discharge voltage. and V3 is the ON voltage.

The operation similar to that of the first pulse signal is repeated for the pulse signals after the first pulse signal (time t0 to time t2) (pulse signals after time t2).

As described above, spark discharge occurs at the ignition plug 7 at the timing when the IGBT 31 is turned off. That is, referring to FIG. 3, spark discharge occurs at the ignition plug 7 at times t1, t3, and t5.

Further, the secondary voltage V, which is the voltage across the secondary coil L2, is applied to the dielectric barrier discharge reactor 8 as a positive pulse voltage during the ON period (time period T1) of the IGBT 31, and is applied to the dielectric barrier discharge reactor 8 during the OFF period (time period T1) of the IGBT 31. During the period T2), it is applied to the dielectric barrier discharge reactor 8 as a negative pulse voltage. That is, referring to FIG. 3, a positive pulse voltage is applied to the dielectric barrier discharge reactor 8 at times t0, t2 and t4, and a negative pulse voltage is applied to the dielectric barrier discharge reactor 8 at times t1, t3 and t5. It is applied to the barrier discharge reactor 8 . As a result, a dielectric barrier discharge occurs at the timing when the polarity of the positive and negative polarities is reversed, and the highly flame-retardant ammonia gas is converted into atmospheric pressure non-equilibrium plasma, generating hydrogen gas, which is more combustible than ammonia gas. It becomes possible to separate and produce from ammonia gas.

According to the ignition system 10 according to the above embodiment, the same pulse signal can be used to perform the ignition discharge to the spark plug 7 and the dielectric barrier discharge for plasmatizing the highly flame-retardant ammonia gas. It becomes possible. Therefore, in the technology for efficiently burning ammonia described above, there is no need for a separate control device for generating the dielectric barrier discharge to generate the required hydrogen gas, thereby suppressing an increase in manufacturing costs. becomes possible.

Further, although the present embodiment has been described using ammonia as the flame-retardant fuel, the present invention is not limited to this. For example, an ammonia compound or other flame-retardant fuel may be used as the flame-retardant fuel, and furthermore, other substances such as carbon-based compounds may be mixed with these as main raw materials. That is, the present invention comprises a combustor body in which the supplied fuel is burned, a swirler provided in the combustor body for feeding the first fuel into the combustor body as a swirling airflow, and a dielectric barrier discharge. A reformer that reforms the first fuel to produce a second fuel with higher combustibility than the first fuel, and a pilot that injects the second fuel with higher combustibility than the first fuel into the combustor body. A burner, a spark plug that ignites the pilot burner, and a control device that controls the ignition operation of the spark plug, and the control device is also applicable to a combustor that controls dielectric barrier discharge in the reformer. is possible.

Further, in the present embodiment, the drive unit 32 controls energization or cutoff of the IGBT 31 using a CPU that performs control processing and arithmetic processing related to combustion control and data and programs necessary for combustion control held in various memories. However, the invention is not so limited. For example, the drive unit 32 may be configured to control energization or cutoff of the IGBT 31 based on at least one of the voltage of the battery 6 and the voltage between the primary coil L1 and the IGBT 31, which is a switching element. good. Also in this case, the same effects as in the present embodiment can be obtained. Furthermore, compared with the present embodiment, the voltage across the secondary coil L2 has a value obtained by multiplying the voltage across the primary coil L1 by the turns ratio, so the value of the voltage across the secondary coil L2 can be easily determined. It is possible to grasp the

Furthermore, in the present embodiment, energy is directly supplied from the secondary coil L2 to the reformer 13 and the spark plug 7, but the present invention is not limited to this. For example, a Zener diode or a resistor may be connected between the secondary coil L2 and the discharge electrode 7a of the spark plug 7, or between the secondary coil L2 and the dielectric barrier discharge reactor 8. may be configured such that a Zener diode or resistor is connected to . Also in this case, the same effects as in the present embodiment can be obtained. Furthermore, compared with this embodiment, it becomes possible to adjust the energy supplied from the secondary coil L2 to the reformer 13 and the spark plug 7. FIG.

While embodiments of the invention have been described, the embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and its equivalents.

Reference Signs List 1 controller 2 combustor 4 combustor body 5 ignition coil 6 battery 7 spark plug 8 dielectric barrier discharge reactor 10 ignition system 13 reformer 14 pilot burner 18 bottom 20 lid 21 valve 22 inlet 23 swirler 24 outlet

Claims (7)

an ignition coil having a primary coil through which a primary current flows and a secondary coil that generates a secondary current by increasing or decreasing the primary current;
a spark plug having at one end a discharge electrode electrically connected to the secondary coil;
a dielectric barrier discharge reactor for generating a dielectric barrier discharge ;
a reformer that reforms the first fuel by the dielectric barrier discharge to generate a second fuel having higher combustibility than the first fuel;
An ignition system in which the discharge electrode of the spark plug and the dielectric barrier discharge reactor are electrically connected. 2. The ignition system of claim 1, wherein a Zener diode or resistor is connected between said secondary coil and said spark plug discharge electrode. 3. The ignition system of claim 1 or 2, wherein a Zener diode or resistor is connected between said secondary coil and said dielectric barrier discharge reactor. Further comprising a battery connected to the primary coil, and an ignition coil drive circuit for controlling the increase or decrease in the primary current of the primary coil,
The ignition coil drive circuit includes:
a switching element connected to the primary coil of the ignition coil;
A driving unit that controls energization or cutoff of the switching element,
4. The driving unit controls energization or cutoff of the switching element based on at least one of a battery voltage and a voltage between the primary coil and the switching element. 10. The ignition system according to claim 1. 5. The ignition system according to claim 4, wherein said driver controls said dielectric barrier discharge within said reformer. an ignition system according to any one of claims 1 to 3;
a combustor body in which the supplied fuel is burned;
a swirler provided in the combustor body for feeding the first fuel into the combustor body as a swirling airflow ;
a pilot burner that injects the second fuel into the combustor body ;
and a control means for controlling the ignition operation of the spark plug,
the spark plug ignites the pilot burner;
The control means is a combustor that controls the dielectric barrier discharge in the reformer. 7. The combustor of claim 6, wherein said first fuel is ammonia gas and said second fuel is hydrogen gas.

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